I happen to be "the other person" in your scenario at this moment. I found someone to be great friends with, including benefits, and all was well but....Life, stress, lack of honest communication and my own faults created a rift. He has moved on for the most part and we barely speak now. I want to hear from him that he made as many bad choices as I did, that even though it seemed right at first, I must remember all things change. Meaning It's okay to let him/her go but do take accountability for any choices you made during this so that person isn't left feeling that they are at fault and you bear no burden. It's important to tell them how you actually feel about what you need to say if you know it will hurt them.